On the Surface Structure of Zeolite (MFI) Crystals

Diaz, I., Kokkoli, E., Terasaki, O. and Tsapatsis, M.

Abstract

Silicalite-1 (structure type MFI) is an important zeolite that, in addition to conventional applications such as adsorption and catalysis and emerging applications such as thin films and membranes, is often used as a model system in studies of zeolite crystal growth. The surface structure of silicalite-1 crystals with two different morphologies (hexagonal prismatic and leaf-shaped platelike crystals), synthesized in the presence of two different structure-directing agents (SDAs) (tetrapropylammonium (TPA) cation and the trimer of TPA, respectively), is elucidated by high-resolution transmission electron microscopy and atomic force microscopy. The differences and similarities in crystal shape and external surface termination are interpreted based on SDA fitting in the crystal structure and adsorption kinetics of the SDAs on the external surfaces of the growing crystals.